The biochemical mechanisms that control rod outer segment cGMP and Ca++ levels will be examined. Each of the peripheral proteins, G-proteins, PDE, rhodopsin kinase and 48K protein will be extracted, purified and reconstituted (recons) singly and in combination with other proteins or stripped rod disk membranes (sRDM). These recons will be analyzed as appropriate for their ability to mimic the activity of normal rod disk membranes (RDM) in binding ATP or GTP, releasing ADP or GDP, hydrolysis of cGMP and speed of arrest of PDE activation and cGMP hydrolysis to determine their enzyme functional integrity. The binding and rate constants for finding will be determined for each of these "RDM-photoaffinity" proteins in darkness and as a function of time after calibrated illumination to determine physical aspects controlling binding and functional role of subunit dissociation correlated with the nucleotide functional studies. A "permeabilized" rod preparation will be developed to study these properties and the controller properties of RDS guanylate cyclase and of Ca++ release and uptake in a system retaining native protein enzyme content but permitting influx and efflux of nucleotides and their products. Attempts will be made to "diagnose" the molecular lesion of some dystropic retinas using techniques and information developed in the above studies.